1. Field of the Invention
The invention relates to the control and prevention of autoimmune disease, in particular rheumatoid arthritis. More specifically, the invention relates to methods and reagents which reduce or prevent the response of a host to arthritogenic peptides which include an amino acid sequence (Q(K/R)RAA) that is homologous to a sequence contained in certain HLA proteins.
2. History of the Prior Art
In humans, autoimmune diseases such as rheumatoid arthritis tend to be associated with particular HLA specificities. Rheumatoid arthritis (RA) in particular is presently believed to be associated on a genetic level with the Class II HLA haplotypes DW4, DW14, DW15 (all with DR4 specificity) and/or DR1. Each of these haplotypes include an amino acid sequence which is commonly referred to as the “susceptibility sequence” (hereafter, “RA susceptibility sequence”; see SEQ ID NOs: 1 and 2). The RA susceptibility sequence is known to vary at one amino acid; to wit, QRRAA (SEQ ID NO: 3) and QKRAA (SEQ ID NO: 2) (hereafter, “Q(R/K)RAA”). More than 90% of adult patients with seropositive RA have also been found to have HLA DR antigens with the RA susceptibility sequence in the third hypervariable region of the molecule. The RA susceptibility sequence has not been implicated in the onset of juvenile RA (JRA), except in patients suffering from severe, seropositive JRA.
The QRRAA (SEQ ID NO: 3) variant of the susceptibility sequence has been identified on HLA haplotypes DW14, DW15 and DR1. The QKRRA (SEQ ID NO: 2) variant has been identified on HLA haplotype DW4. Highly conserved homologs of the variants have also been identified in the Epstein-Barr virus glycoprotein gp110, as well as the dnaJ heat shock proteins from Escherichia coli, as well as the bacterial species Klebsiella, Ptoteus, Salmonella, and Lactococcus. 
In 1992, Albani, et al., J. Clin. Invest., 89:327–331 (1992) published a report indicating that they had expressed and purified recombinant dnaJ (rdnaJ). The purified rdnaJ was specifically bound by antisera raised in rabbits against the RA susceptibility sequence from DW4 proteins. Antisera raised against rdnaJ also bound the intact DW4 protein in vitro as well as DW4 homozygous B lymphoblasts. No role or mechanism for in vivo activity on the part of rdnaJ in rheumatoid arthritis was proposed.
One approach to utilize the RA susceptibility sequence to treat RA has been proposed which would vaccinate humans against RA with certain RA susceptibility sequence peptides derived from known human HLA peptides (see, published PCT application, WO 9014835 (filed May 31, 1990), Carson, et al., inventors).
Another therapeutic modality for controlling the immune response to bacterial antigens has been proposed in U.S. Pat. No. 4,732,757 to Stolle, et al. Stolle, et al. proposed administering IgG antibodies raised in cow's milk against a broad spectrum of intact bacteria which typically reside in the human gastrointestinal tract. The IgG tested by Stolle, et al., were raised against a mixture of intact organisms without targeting specific bacterial antigens. This patent issued prior to the identification of the RA susceptibility sequence in certain bacterial heat shock proteins, including dnaJ. The antisera described by Stolle, et al. were not, therefore, directed toward RA susceptibility sequence peptides.
None of these approaches to treating RA specifically target arthritogenic peptides before the peptides are presented to the systemic immune system of an RA patient. A need, therefore, exists for a treatment which will not only ameliorate systemic responses by an RA patient to arthritogenic peptides, but will also prevent pathogenic exposure of the patient to the arthritogenic peptides through the release of such peptides from the patient's GI tract into systemic circulation. Ideally, such treatments will be provided either before the patient develops RA or in the early stages of the disease; thus, a need also exists for a method of identifying persons who are genetically and immunologically predisposed to develop RA.
The present invention addresses each of these needs.